Elevated liver (CK) values and cycling

Really random question.

Basically I’ve enrolled in a clinical trial (don’t judge, but I really want a new power meter :slight_smile: ). At the screening the Doctor has said there will be training restrictions due to muscular breakdown showing as elevated liver values (creatine kinase) which would mean I’d have to restrict/ cut out weightlifting and running, but there was no specific mention of cycling…

I’ve googled and done a search on the TR forum but haven’t seen any form of answer.

I’m happy to keep intensity low and avoid taxing intervals, but how demanding is cycling from the viewpoint of muscular damage? I have a relatively light spin of approx 90rpm, I’ve been working on lower intensities recently as I basically have no aerobic base so I figured I’d start to build one.

Anyone have any cycling specific experience/links? Ideally I’d like to be able to train “something”, if I can’t I probably won’t enroll. Thanks!

I haven’t done any online searching but it would surprise me if clinical lab markers like myoglobin, CK, LDH, D-dimer, thrombin complexes, hsCRP, cardiac troponin would be up after a rough workout.

Low intensity for short duration should obviously be less of a problem but where the line is remains hard to tell

CK isn’t a liver marker. There are actually 2 types: brain and muscle, and you can actually have 3 combinations (BB, MB, MM). When doctors says elevated CK, it’s usually the muscle type and it’s usually when talking about heart attacks. But any muscle damage can raise it. To what extent, that’s another story. Huge muscle damage causing rhabdo causes a huge CK increase. Exercise will raise it, any exercise, and for a trial, that can skew the results. They want to remove all the extraneous variables.

Basically, CK is an enzyme that combines ATP (energy) and creatine into a storage form phosphocreatine, for later use. Hence the role in muscles and why bodybuilders supplement creatine.

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Thank you!

But… what I’m wondering is how much “damage” do the pettit’s/Baxter’s and lazy mountains cause? Or is that even quantifiable?

my creatine kinase has been elevated in the past after excercising (boxing)

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It is technically quantifiable, but you’d have to know your baseline CK and retest after the workout. Which isn’t feasible. Working out/exercising is muscle damage, that’s the point, to rebuild stronger muscle. And some exercise does more. Weightlifting will probably raise your CK more than cycling. I couldn’t find a lot of studies but they looked at CK levels in Leadville Ultramarathon runners (extreme case) and saw increases up to over 14,000 from a baseline of around 120. This is an extreme case obviously. How much a 2 hour endurance ride will raise it is another story, but it’s likely it could be elevated some.

The thing to think about is how it will affect the study. If this is for a new medication, they’re looking at side effects, one of which is CK elevation as you stated. Statins are a big category that can cause this. So if that’s a known side effect, or it’s a new medication and they don’t know what the side effects are, and they’re measuring CK levels, you artificially elevate yours with exercise, and that will get attributed to the medication. Will this skew the study? Maybe, it’s hard to tell, but it could. They’re looking to remove those variables to get an accurate study, and exercise in this case can mess with that. From a medical and scientific standpoint, I’d say to disclose everything to the researchers and if they tell you you can’t do the study, well that’s too bad. But if you want to continue working out, nobody can stop you.

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Ok, makes complete sense. Baseline tests were yesterday, il see if I get a call back then reassess.

Man, I couldn’t imagine being sedentary for 6 weeks (without injury).

Thank you, you’ve really explained it well

I can’t say I have seen extremely elevated CK levels from cycling training (i.e. within ‘normal’ levels), that training being a mix of SS, HIIT and base miles.

I have seen extreme CK levels through weight sessions, but even then normal levels after 3 days.

I would just talk with the people doing the study and see what you can do, because I agree, 6 weeks without exercising would be terrible. I don’t think they’d expect you to do nothing, but see what they say.

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